How To Identify The Quality Of Commonly Used Plywood Products
Nowadays, plywood is a three-layer or multi-layer plate material made by peeling wood segments into veneers or planing wood blocks into thin wood, and then gluing them with adhesives. Generally, odd-numbered veneers are used, and the fiber directions of adjacent veneers are glued together in a straight line.
In order to improve the anisotropic properties of natural wood as much as possible, make the plywood properties uniform and the shape stable, plywood generally follows some principles and key points in structure. One is symmetry, and the other is that the fibers of adjacent veneers are straight. The principle of symmetry requires that the veneers at both ends of the symmetry center plane of the plywood should be symmetrical to each other regardless of the nature of the wood, the thickness of the veneer, the number of layers, the fiber direction, the moisture content, etc. In the same plywood, veneers of a single tree species and thickness can be used, or veneers of different tree species and thicknesses can be used, but any two layers of symmetric veneers at both ends of the symmetry center plane must be of the same tree species and thickness, and the face and back boards are allowed to be of different tree species.
Plywood manufacturers know that plywood is a common building and decoration material in our lives, but there are many products on the market. If we want to use qualified products, we also need to distinguish the quality of the products. In order for the structure of plywood to meet the above two basic principles, its number of layers should be an odd number, so plywood is generally made into three layers, five layers, seven layers and other odd layers. The surface veneer is called the surface board, the inner veneer is called the core board, the front surface board is called the panel board, and the back surface board is called the back board. In the core board, the fiber direction is parallel to the surface board. It is called the long core board or the middle board. When forming the cavity table board blank, the panel board and the back board must face outward.
